Based on the NCAR/NCEP reanalysis data， the weather situation and water vapor transport characteristics of two typical rainstorm weather processes in Sanjiangyuan on July 22-23 （"0722"） and August 2-3 （"0802"） were analyzed firstly.Then， the WRF model was used to output data for driving the HYSPLIT model to quantitatively analyzing the water vapor transport of the two storms.The results show： （1） The main influence systems of the two rainstorms are the vortex and shear lines formed in the eastern region of Sanjiangyuan and the evolution and advance and retreat of the vortex system has great influence on the intensity and fall area of the rainstorms.（2） The HYSPLIT model uses the high-resolution data output from the WRF model as the initial field and the simulation works well.（3） There are three main moisture transport routes for the “0722” rainstorm： 10 days before the rainstorm， the gas blocks in the northwest path were located in the western region of Xinjiang and entered the Sanjiangyuan via the northern Qinghai-Xizang Plateau， the moisture transport contribution rate is 16%； The air parcels in the southwest path originate from the north of the Bay of Bengal and are transported to Sanjiangyuan through the water vapor transport channel of the Yarlung Zangbo River Grand Canyon， with the water vapor transport contribution rate is 41.5%； Water vapor in the southwest path existed in Guangxi 10 days ago and transported to the rainstorm area through Sichuan and other places， with water vapor transport contribution rate acbeing 42.5%.（4） The water vapor of the "0802" rainstorm is mainly transported to the Sanjiangyuan area via four routes： one route is southwest， and the water vapor of the Bay of Bengal is transported to the rainstorm area through the Yarlung Zangbo River Grand Canyon， the water vapor transport contribution rate is 28%.The remaining three are southeast routes： ten days ago， the main source of water vapor appeared in Guizhou and Hunan and is transported to Sanjiangyuan in the northwest direction， the contribution rate of water vapor transportation of the three routes being 23%， 23% and 26%， respectively.（5） In general， the main water vapors for the two rainstorms come from the southwest and southeast paths.The water vapors in the southwest path come from the Bay of Bengal and are transported to the rainstorm area through the Water vapor transport channel of the Yarlung Zangbo River Grand Canyon.The water vapors along the southeast path are transferred-toward the northwest from Guangdong and Hunan to the rainstorm area.For the rainstorm of "0722"， there are also water vapors transport along the northwest path， which has a small contribution rate.